<template>
  <div class="file-upload">
    <div class="file-upload-container" @click.prevent="triggerUpload" v-bind="$attrs">
      <slot v-if="fileStatus === 'loading'" name="loading">
        <button class="btn btn-primary" disabled>正在上传...</button>
      </slot>
      <slot v-else-if="fileStatus === 'success'" name="uploaded" :uploadedData="uploadedData">
        <button class="btn btn-primary">上传成功</button>
      </slot>
      <slot v-else name="default">
        <button class="btn btn-primary">点击上传</button>
      </slot>
    </div>
    <input type="file" class="file-input d-none" ref="fileInput" @change="handleFileChange" />
  </div>
</template>
<script lang="ts">
import { defineComponent, ref, PropType, watch } from 'vue'
import axios from '@/utils/axios'
type UploadStatus = 'ready' | 'loading' | 'success' | 'error'
type CheckFunction = (file: File) => boolean
export default defineComponent({
  props: {
    action: {
      type: String,
      required: true
    },
    beforeUpload: {
      type: Function as PropType<CheckFunction>
    },
    uploaded: {
      type: Object
    }
  },
  inheritAttrs: false,
  emits: ['file-uploaded', 'file-uploaded-error'],
  setup(props, context) {
    const fileInput = ref<null | HTMLInputElement>(null) // 上传文件 input ref dom
    const fileStatus = ref<UploadStatus>(props.uploaded ? 'success' : 'ready') // 上传状态
    const uploadedData = ref(props.uploaded) // 上传信息
    // 监听上传信息
    watch(
      () => props.uploaded,
      newValue => {
        if (newValue) {
          fileStatus.value = 'success'
          uploadedData.value = newValue
        }
      }
    )
    const triggerUpload = () => {
      if (fileInput.value) {
        fileInput.value.click()
      }
    }
    const handleFileChange = (e: Event) => {
      const currentTarget = e.target as HTMLInputElement
      if (currentTarget.files) {
        const files = Array.from(currentTarget.files)
        if (props.beforeUpload) {
          const result = props.beforeUpload(files[0])
          if (!result) {
            return
          }
        }
        fileStatus.value = 'loading'
        const formData = new FormData()
        formData.append('file', files[0])
        axios
          .post(props.action, formData, {
            headers: {
              'Content-Type': 'multipart/form-data'
            }
          })
          .then(resp => {
            fileStatus.value = 'success'
            uploadedData.value = resp.data
            context.emit('file-uploaded', resp.data)
          })
          .catch(error => {
            fileStatus.value = 'error'
            context.emit('file-uploaded-error', { error })
          })
          .finally(() => {
            if (fileInput.value) {
              fileInput.value.value = ''
            }
          })
      }
    }
    return {
      fileInput,
      triggerUpload,
      fileStatus,
      uploadedData,
      handleFileChange
    }
  }
})
</script>
